A. Field of the Invention
This invention relates to copper promoted highly active nickel-silica catalysts having stabilized high nickel surface areas which contain very little quantities of alkaline metals, their preparation and use in the hydrogenation of organic compounds. In one aspect, this invention relates to the addition of copper in the preparation of a massive nickel hydrogenation catalyst thereby facilitating the low temperature reduction of the catalyst. In another aspect, this invention relates to the preparation of novel activated nickel copper hydrogenation catalysts. In yet another aspect, this invention relates to charging the copper nickel silica catalyst into the hydrogenation plant without undergoing the customary prereduction and stabilization steps that are required for the commercial hydrogenation catalysts now being employed.
B. Description of the Prior Art
The so-called activation of supported nickel catalysts, i.e., the reduction of nickel oxide before the catalyst is utilized, is usually conducted at temperatures which are very high in comparison to those at which the reduction of bulk nickel oxide can be completed. It is a well-known fact that supported nickel oxide is more difficult to reduce than when unsupported and that high reduction temperatures promote sintering of nickel. It is thought that, in many instances, a better activity and/or a better poison capacity could be obtained, if lower reduction temperatures could be used.
In conformity with the experience of people concerned with catalyst manufacture, recent publications suggest that various promoters of nickel catalyst are effective not because of some modification of the catalytic properties, but as a consequence of a better activation.
A. Roman and B. Delmon in an article from the Journal of Catalysis, 30, pp. 333-342 (1973) entitled "Promoter and Carrier Effects in Reduction of NiO/SiO.sub.2 " have described the hydrogen reduction of nickel oxide deposited on silica by employing copper deposited onto the surface of the catalyst.
In another paper published in the Journal of Catalysis, 22, pp. 204-212 (1971) entitled "Increase of Reducibility of NiO by H.sub.2, Due to Pretreatment with Salt Solutions" by H. Charcosset, R. Frety, A. Soldat and Y. Trambouze, also describes the use of copper in the treatment of pure nickel oxide to make the reduction easier. In this paper, they also impregnated the nickel oxide catalyst with various salt solutions followed by drying and extraction with water. They then compared the reduction of these catalysts in hydrogen to see which metals had the most effect. They indicated most pronounced effects occur with copper, platinum, palladium, ruthenium, rhodium, osmium, iridium which they stated are related to a cationic exchange with surface nickel during impregnation.
More recently, in a paper published in the Journal of Catalysis, 24, pp. 283-296 (1972) entitled "Catalytic Hydrogenolysis and Dehydrogenation Over Copper-Nickel Alloys" by J. H. Sinfelt, J. L. Carter and D. J. C. Yates, there is described the surprisingly large effects on suppression of hydrocracking from the incorporation of small amounts of copper into nickel in a copper/nickel alloy.
The patent literature also includes descriptions of nickel catalysts which contain copper. One example of such a description is disclosed in U.S. Pat. No. 2,750,261 to Ipatieff et al. In this patent there is disclosed a process for preparing catalyst useful in the production of hydrogen comprising the steps of co-precipitating a mixture of nickel and copper ions onto a carrier such as diatomaceous earth. A comparison of the catalyst prepared in accordance with Example II of this patent with the instant catalyst is disclosed in Examples 6 and 7 of the instant application.
The copper promotion of the subject invention relates to the massive nickel catalyst described in U.S. Pat. Nos. 3,697,445 and 3,859,370. These patents describe catalysts having high nickel surface area and the relationship between the high nickel surface area and their activity. The nickel surface area is measured by hydrogen chemisorption, after reduction at 400.degree. C., in the manner described by Yates, Taylor and Sinfelt, in J. Am. Chem. Soc., 86, 2996 (1964).
In U.S. Pat. No. 3,859,370 there is described a process for carefully controlling critical conditions to form these high nickel surface area catalysts wherein nickel catalysts precipitated in the presence of porous solid particles can be made which have a nickel surface area greater than about 70 m.sup.2 /g, preferably 75 to 100 m.sup.2 /g and catalytic activity for hydrogenation several times greater than the previously known nickel catalysts.
The massive nickel catalysts described in the aforesaid U.S. Pat. Nos. 3,697,445 and 3,859,370 have proven to be active hydrogenation catalysts in laboratory and pilot plant runs when they are activated by reduction at 400.degree. C. However, there is a need to have such a catalyst that can be activated at the lower temperatures than are normally obtainable in the commercial hydrogenation plant which is approximately 200.degree. C.